The broad objective of the proposed research is to define the neural mechanisms that govern the perceptual processing of complex sounds at the level of the cerebral cortex. The long-term goal is to develop an experimental model by which to test hypotheses about the role of auditory cortical neurons in feature abstraction, percept formation, and object recognition. Of particular relevance to human health is how these neural mechanisms mediate the discrimination and recognition of complex pitch, timbre, and speech, which are disrupted following injury to auditory cortex. The proposed experiments will be carried out under the direct supervision of the sponsors and will be the focus of an intensive laboratory training experience designed to prepare the principal investigator for a research career dedicated to the study of cortical auditory functions. The specific aims of the proposed research examine the representation of spectral and temporal information in single neurons and in anatomically and biochemically differentiated fields of neurons in primate auditory cortex. The experimental design seeks to apply to the study of cortical auditory functions modern laboratory techniques that have greatly advanced knowledge about the functional anatomy of visual cortex in recent years. These include methods of mapping the distribution of a cellular enzyme subserving oxidative metabolism, measuring regional metabolic activity during stimulus processing, recording single unit activity during stimulus processing, and correlating these physiological properties with the cytoarchitectonic organization of functionally specialized zones.